Alloy



Patented Aug. 3, 1937 UNITED STATES PATENT OFFICE Firth-Sterling Steel Company, McKeesport,

Pa., a corporation 01' Pennsylvania No Drawing. Application November 17, 1934, Serial No. 753,475

9 Claims.

This invention relates generally to alloys, and more particularly to cast non-ferrous alloys useful for forming cutting tools, wire drawing dies, dies for forming metal, extrusion dies, wear resisting parts and the like.

Alloys for such purposes, in addition to being strong enough to withstand the stresses to which they are subjected, must have the property of red hardness so that a tool made therefrom will maintain its cutting edge when it is red hot. The alloy must also possess abrasive hardness either for wear resisting purposes or for providing hard crystals necessary in cutting tools;

The alloy of the present invention has these and other desirable properties to a marked extent. The alloy contains carbon, tungsten, cobalt and vanadium. The carbon may vary between 2% and 4%, preferably between 2.0% and 3.5%. The tungsten may be present in amounts between 15% and 50%, although it is preferably between 30% and 40%. The cobalt may be between 15% and 60%, preferably from 40% to 50%. The vanadium is between 5% and 30%, preferably from to 20%.

The alloy may be made by melting the ingredients in the proper proportions in any suitable furnace, such as a crucible furnace or an electric furnace, preferably an electric furnace of the induction type which, due to its construction, sets up a flow of the molten metal and eliminates the necessity of stirring.

A fusible slag forming material, for example glass, is melted with the charge to provide a protecting layer for the alloy which prevents oxidation. The charge is heated to a temperature sufilcient to melt it, such temperatures usually ranging between 1750 C. and 2000 C. The'alloy is cast into the approximate shape desired and then finished by grinding. I prefer to use molds made from graphite, although other molds, such as sand, copper or other metal, may beemployed. Graphite molds are easily machinable and, accordingly, can be made to the desired shape in an economical manner.

The charge may be made up of carbon, tungsten, cobalt and vanadium in the proportions necessary to produce the alloy, but it is preferred to provide the carbon as a carbide of one or more of the metals such as vanadium or tungsten. The-use of carbides of the metals for imparting the necessary carbon to the alloy provides a convenient and accurate method in which the carbon is evenly distributed throughout'the melt. Alloys of the present type have very high melting points, and it is therefore advisable to use a 5 carbide of one or more of the metals in order to insure homogeneity in the alloy. It is specifically preferred to employ vanadium carbide rather than tungsten carbide for imparting to the alloy the desired carbon content. Vanadium carbide has 10 a carbon content of approximately 18%, whereas tungsten carbide has a carbon content of approximately 6%.

My preferred composition contains about 3% carbon, 36.5% tungsten, 45.5% cobalt and about 15 15% vanadium. Such alloy can be produced by melting about 18% vanadium carbide, 36.5% tungsten and 45.5% cobalt. On the other hand, if tungsten carbide was employed in place of vanadium carbide, the alloy containing 36.5% 20 tungsten would only contain approximately 2.2% carbon, and this is below the 3% carbon which is preferred. This deficiency in carbon is accentuated where the alloy contains only 15% of tungsten, the carbon in this case being only about 25 .9%.' It will be seen therefore that vanadium carbide contains vanadium and carbon in such proportions that the desired percentages of vanadium and carbon can be produced in the final alloy without the addition of carbon in other form.

In order to obtain an alloy which can be melted at temperatures which can be produced practically, it is preferred that the alloy contain tungsten and cobalt approximately in the proportions of the tungsten-cobalt eutectic. This eutectic contains 44.5%-tungsten and 55.5% cobalt and melts at a temperature of approximately 1480 C. Thus, if it is desired that the alloy contain, for example, 15% vanadium and 3% carbon, the remaining 82% of the alloy is preferably constltuted by tungsten and cobalt in the eutectic proportions of 44.5% tungsten and 55.5% cobalt. This alloy, accordingly, would contain approximately 3% carbon, 36.5% tungsten, 45.5% cobait, and 15% vanadium.

Although the essential constituents of my alloy are carbon, tungsten, cobalt and vanadium, it may also contain iron, nickel, chromium, tantalum, columbium, molybdenum, etc., up to a total of about 5% without radically changing the properties of the alloy, and also it may contain small amounts of silicon and manganese as impurities.

My alloy has been tested against various ferrous and non-ferrous cast alloys now on the market and these tests have proved my alloy superior in the cutting of steel. Tables I and 11. show the results of certain of these tests:

Table I Cutting conditions Si Mn 8 1 Material cut Axle steolAnalysis .43 .20 .71 .MJBO Hardness"-.. 187 BN Depth 01 cut" 0.125. Feed per mm. 0.03l25. Cutting speed 110 FPM-N0 coolant" O Si Mn Ni W Cr Va 00 Fe AllOyl 2.75 .42 .02 35.97 14.71 44.87 1.26 Alloy2 .2) .46 .54 .88 29.64 49.59 Alloy3 1.90 .26 .24 16.81 3412 44.88 1.89

QZF Tool lilo-Second test Alloy l- A" sq. bit..- 149.25 min. 133.57 (still cutting. Alloy 2%" sq. bit..- 9.25 min. 9. 83 Alloy 3%" sq. bit 50.25 min. 74. 17

Table II Cutting conditions C Si Mn 8 P Ni Material out.-- SAE 2340Analysis 43 25 .70 .031 .035 3. 56 Hardness...- 250 BN. Depth of cut. 0.l25" Feed per rev. 0. Cutting speed. 100 FPMN0 coolant C Si W Cr Va Co Fe Ni Alloyl 2.40 .25 36.51 14.87 45.48 .40 .10 Al1oy2 1.90 16.81 34.12 44.88 1.89 .24

Tool life Alloy l%" sq. bit 90.05 min. Alloy 2% sq. bit 30.92 min.

In these tables, alloy 1 designates an alloy made in accordance with the present invention. Alloys 2 and 3 are other commercial alloys now on the market. As shown in Table I, alloy 1 had a tool life from two to three times as long as alloy 3, and approximately fifteen times as long as alloy 2. In Table II, alloy 1 had a tool life-zapproximately three times as long as 'al- Although I have described in detail the preferred composition of my alloy and the preferred method of making it, it is to be understood that the invention may be otherwise embodied or practiced within the scope of the following claims.

I claim:

1. A melted and cast alloy composed of about 2% to 4% carbon, 15% to 50% tungsten, 15% to 60% cobalt, and 5% to 30% vanadium.

2. An alloy composed of about 2% to 4% carbon, 30% to 40% tungsten, 40% to 50% cobalt, and to 20% vanadium.

3. An alloy composed of carbon, tungsten, co-

balt and vanadium, the carbon being about 2% to 4%, the vanadium about 5% to 30%, the

tungsten about to 50%, and the cobalt about 15% to 60%, the tungsten and cobalt being substantially in the ratio to each other of 44.5% to 55.5%.

4. An alloy composed of carbon, tungsten, co-

bait and vanadium, the carbon being about 2.0% to 3.5%, the vanadium about 10% to 20%, the tungsten about to the cobalt about 40% to the tungsten and cobalt being substantially in the ratio to each other of 44.5% to 55.5%.

5. An alloy composed of carbon, tungsten, co-

. ball; and vanadium, the carbon being about 2% to 4% and the vanadium about 5% to 30%, the remainder of the alloy consisting substantially of tungsten and cobalt substantially in the ratio of 44.5% tungsten to 55.5% cobalt.

6. An alloy composed of carbon, tungsten, cobalt and vanadium, the carbon being about 2% to 4% and the vanadium about 10% to 20%, the remainder of the alloy consisting substantially of tungsten and cobalt substantially in the ratio of 44.5% tungsten to 55.5% cobalt.

7. A melted and cast alloy composed of about 2% to 4% carbon, 15% to 50% tungsten, 15% to cobalt, and 5% to 30% vanadium, said alloy being made by melting a carbide of one of said metals together with the remaining constituents required to form the alloy.

8. An alloy composed of about 2% to 4% carbon, 15% to 50% tungsten, 15% to 60% cobalt, and 5% to 30% vanadium, said alloy being made by melting vanadium carbide together with the remaining constituents required to form the alloy.

9. An alloy composed of about 2% to 4% carbon, 15% to 50% tungsten, 15% to 60% cobalt, and 5% to 30% vanadium, said alloy being made by melting vanadium carbide, tungsten and cobait.

ELMER B. wEwn'. 

